As a method for obtaining an image having a wider angle of view than the image pickup angle of view of an image pickup apparatus, there is a known method of picking up a plurality of images while shifting each picked-up area to small extent so that two successively picked-up images have shared portions (hereinafter referred to as a “division pickup method”).
As a conventional technique relating to the division pickup method, Japanese Patent Laid-Open No. H06-121226 (FIG. 7) discloses a technique of generating a single image having a large angle of view from a panning image taken by a video camera. According to the technique of Japanese Patent Laid-Open No. H06-121226, a motion vector is calculated from a panning image by image pattern matching, a shared image area (a crosshatched portion at S5 in FIG. 7) is detected, and the shared image area and the following portion are combined (a memory 20C at S5 in FIG. 7).
Japanese Patent Laid-Open No. H06-121226 also discloses reproduction and displaying of the thus-generated synthesized image data (FIG. 20). According to the technique of Japanese Patent Laid-Open No. H06-121226, a size-reduced version of a whole synthesized image is displayed in a lower right area (sub-screen) of a display unit, while a portion (crosshatched portion of the sub-screen) of the whole synthesized image is displayed on a main screen set from a middle to a left side. In other words, a portion of the size-reduced image is enlarged and displayed on the main screen. If the size-reduced image is directly enlarged, the resolution is insufficient. Therefore, image data corresponding to a portion to be enlarged and displayed is read out from a storage medium again.
Japanese Patent Laid-Open No. 2005-197785 discloses a method for displaying a plurality of related picked-up images without synthesis (FIG. 14). According to Japanese Patent Laid-Open No. 2005-197785, a play list with which the order of reproduction of a plurality of related picked-up images is controlled is generated during image pickup. If a user selects this play list for reproduction, the user can sequentially browse picked-up images within a whole image pickup range while maintaining the resolution, without performing a complicated operation.
However, in the technique of Japanese Patent Laid-Open No. H06-121226, every time an enlarged display portion of a synthesized image is moved, corresponding image data needs to be read out from a storage medium. Therefore, it takes a time to read out image data, and there are cases in which the enlarged display portion is not smoothly moved. Also, since the user needs to select a portion to be enlarged and displayed, a complicated procedure is required to display a whole synthesized image with its original high image quality.
In the technique of Japanese Patent Laid-Open No. 2005-197785, displayed images are switched in units of a picked-up image. Therefore, it is not easy for the user to intuitively recognize the relevance between successively displayed picked-up images.